First to answer Monsta. The resistors are the Vishay Dale CCF60 series, 3/4 watt, not the CCF50's. The tants are Vishay Type 173D.
Hey Photi. When you say "seen" do you mean you looked under the silicon that's between the caps and read the voltage rating? I'm also just commenting on Dual and Triple Mesa amps. Many people who see the big orange caps just assume they are 630V because that's what the suppliers sell. Every Triple and Dual I've worked on has used 400v 715P series caps. The inter-stage voltages are such in these amps that over a 400v cap is not needed. The use of 400v caps keeps cost lower and saves board space. You can fit the 400's on this board. I didn't use them because I didn't want to stock up on caps I already have the same value of for repairs on other amps. The Epcos are cheaper, and are proven in several popular amps designs, and gives more space between components.
Mesa initially used carbon comp resistors where 1 or 2 watt values were needed on the board(Early 90's). Then they went to metal oxide, and on to these skinny black wirewound resistors for which I'd have to look up the series. Some of the values for the Vishay CCF60, that Mesa originally used carbon comps for, was due to how much volume you could order of values that people didn't commonly use. As the years went on, Mesa replaced the carbon comps and blue metal films, for which they didn't stock the CCF60's for at that time. You'll still see blue metal films in different Mesa amps across the product line. I used carbon comp and blue metal films in various spots because I would have had to order 5,000 of certain less common values to get them from Mouser.